The present invention relates to floor polishers or burnishers and, more particularly, to so-called high speed burnishers. As used herein, "high speed" refers to rotary burnishing machines wherein the floor-contacting burnishing pad is rotated at an angular velocity greater than 1,000 revolutions per minute. Typically, such machines may operate at speeds up to 1,800 or 2,000 r.p.m. The present invention is an improvement of the high speed floor burnisher disclosed in the copending U.S. application Ser. No. 787,269, filed Oct. 15, 1985 and entitled "Improvements in High Speed Floor Burnisher".
The floor burnisher disclosed in that application has a driver assembly for the burnishing pad which includes a rotatably driven hub which carries the burnishing pad, the hub and pad being enclosed within a vacuum shroud. The rotating motion of the hub and burnishing pad generates a radial air flow which is directed from beneath the shroud to associated collection means. In that device, the air flow is generated by a plurality of spaced-apart and radially outwardly extending fins or vanes on the hub. But these fins increase the cost of manufacture of the hub and necessitate the use of a shroud which is large enough to encompass the fins.
The invention of the copending application utilizes a flexible backing plate for supporting the burnishing pad which facilitates maintenance of uniform contact of the entire working area of the burnishing pad with the floor. The backing plate has an outer depending retaining flange to prevent radial outward expansion of the burnishing pad. The flange also assists in positioning the burnishing pad.
While the burnishing machine disclosed in the copending application is of the type in which the burnishing pad is coaxial with the drive motor shaft, it is desirable to provide a machine which affords the benefits of that device in a machine of the type which utilizes a rear-mounted motor and a center caster, such as that disclosed in U.S. Pat. No. 4,365,377.